The present invention relates generally to the field of media labeling. In particular, the invention relates to methods and systems for power calibration of a laser for media labeling.
Digital media, such as compact discs (CDs) or digital video discs (DVDs), are a popular form of storage media. Recently, writable digital media have become increasingly popular among users for storing personalized data, including creating their own set of musical compilations, pictures, etc. Once the user has stored or written digital data onto the medium, the user may label the medium by either writing on the medium by hand or affixing a printed label onto the medium using an adhesive.
More recently, systems have been developed for imprinting a labeling layer on a digital medium using a laser of the disc drive. In such systems, laser energy is applied to activate the labeling layer to produce either a grayscale or a color image. In such systems, application of the proper energy level through a corresponding laser power setting is critical. With too low power, the image formed may be faint and may fade with time. If too high of a power setting is used, ablation of the labeling layer may occur.
Determination of the appropriate laser power to use for such imprinting can be difficult. Typical calibration is performed by sensing the output power at the front sense diode of the laser unit. However, dust accumulation on the objective lens of the optical pick-up unit can hinder proper calibration using the front sense diode.